1 | # ---------------------------------------------------------------------- |
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2 | # COMPONENT: dragdrop - drag-n-drop support for widgets |
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3 | # |
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4 | # Derived classes inherit the basic drag-n-drop support from this |
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5 | # widget class. Widgets can register themselves as drag-n-drop |
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6 | # sources and also as targets. |
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7 | # |
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8 | # Derived classes should overload the following methods: |
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9 | # |
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10 | # dd_get_source .... examines click point and returns drag data |
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11 | # |
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12 | # dd_scan_target ... scans target at drop point and returns 1 if |
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13 | # data is accepted, and 0 if rejected |
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14 | # |
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15 | # dd_finalize ...... handles final drag-and-drop operation, |
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16 | # transferring data from the start widget |
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17 | # to the final target. Called with "-op start" |
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18 | # on the starting widget, and "-op end" on the |
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19 | # target widget. |
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20 | # |
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21 | # ====================================================================== |
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22 | # AUTHOR: Michael McLennan, Purdue University |
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23 | # Copyright (c) 2004-2010 Purdue Research Foundation |
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24 | # |
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25 | # See the file "license.terms" for information on usage and |
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26 | # redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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27 | # ====================================================================== |
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28 | package require Itcl |
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29 | |
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30 | itcl::class Rappture::Dragdrop { |
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31 | public method dragdrop {option args} |
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32 | |
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33 | private method _get_source {widget x y} |
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34 | private method _do_scan {x y {option indicate}} |
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35 | private method _do_drop {x y} |
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36 | |
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37 | # derived classes override these methods |
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38 | protected method dd_get_source {widget x y} |
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39 | protected method dd_scan_target {x y data} |
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40 | protected method dd_finalize {option args} |
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41 | |
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42 | private variable _enabled 1 ;# set to 0 to disable drag-n-drop |
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43 | private variable _dragwin "" ;# widget controlling drag-n-drop cursor |
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44 | private variable _dragowner "" ;# mega-widget that initiated drag-n-drop |
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45 | private variable _dragx "" ;# drag-n-drop started at this x |
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46 | private variable _dragy "" ;# drag-n-drop started at this y |
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47 | private variable _dragdata "" ;# description of drag-n-drop source data |
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48 | private variable _lastcursor "" ;# cursor before start of drag-n-drop |
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49 | private variable _lasttarget "" ;# last target found by _do_scan |
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50 | |
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51 | set dir [file dirname [info script]] |
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52 | private common _dcursor "@[file join $dir images drag.xbm] [file join $dir images dragm.xbm] black white" |
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53 | } |
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54 | |
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55 | # ---------------------------------------------------------------------- |
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56 | # USAGE: dragdrop protocol |
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57 | # USAGE: dragdrop enabled ?<boolean>? |
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58 | # USAGE: dragdrop source <widget> |
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59 | # USAGE: dragdrop indicate -from <w> -to <w> -x <x> -y <y> -data <data> |
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60 | # USAGE: dragdrop finalize -op <dir> -from <w> -to <w> -x <x> -y <y> -data <data> |
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61 | # USAGE: dragdrop cancel |
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62 | # |
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63 | # Derived classes use this to register component widgets as drag-n-drop |
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64 | # sources and targets. |
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65 | # ---------------------------------------------------------------------- |
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66 | itcl::body Rappture::Dragdrop::dragdrop {option args} { |
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67 | switch -- $option { |
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68 | protocol { |
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69 | return "1.0" |
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70 | } |
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71 | enabled { |
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72 | if {[llength $args] == 0} { |
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73 | return $_enabled |
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74 | } elseif {[llength $args] != 1} { |
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75 | error "wrong # args: should be \"dragdrop enabled ?boolean?\"" |
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76 | } |
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77 | set state [lindex $args 0] |
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78 | set _enabled [expr {($state) ? 1 : 0}] |
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79 | return $_enabled |
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80 | } |
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81 | source { |
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82 | set widget [lindex $args 0] |
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83 | bind $widget <ButtonPress> [itcl::code $this _get_source %W %X %Y] |
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84 | bind $widget <B1-Motion> [itcl::code $this _do_scan %X %Y] |
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85 | bind $widget <ButtonRelease> [itcl::code $this _do_drop %X %Y] |
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86 | } |
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87 | indicate { |
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88 | array set params $args |
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89 | return [dd_scan_target $params(-x) $params(-y) $params(-data)] |
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90 | } |
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91 | finalize { |
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92 | return [eval dd_finalize drop $args] |
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93 | } |
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94 | cancel { |
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95 | dd_finalize cancel |
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96 | } |
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97 | default { |
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98 | error "bad option \"$option\": should be protocol, source, indicate, finalize, cancel" |
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99 | } |
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100 | } |
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101 | } |
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102 | |
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103 | # ---------------------------------------------------------------------- |
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104 | # USAGE: _get_source <widget> <x> <y> |
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105 | # |
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106 | # Invoked when the user clicks on a widget to start a drag-n-drop |
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107 | # operation. Saves the <x>,<y> coordinate, and waits for a _do_scan |
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108 | # call. If the user drags the mouse a short distance away from the |
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109 | # click point, then the drag-n-drop operation begins. |
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110 | # ---------------------------------------------------------------------- |
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111 | itcl::body Rappture::Dragdrop::_get_source {widget x y} { |
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112 | set _dragowner "" |
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113 | set _lasttarget "" |
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114 | |
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115 | set winx [expr {$x-[winfo rootx $widget]}] |
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116 | set winy [expr {$y-[winfo rooty $widget]}] |
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117 | set d [dd_get_source $widget $winx $winy] |
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118 | |
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119 | if {"" != $d && $_enabled} { |
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120 | set _dragwin $widget |
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121 | set w $widget |
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122 | while {$w != "."} { |
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123 | if {[catch {$w dragdrop protocol}] == 0} { |
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124 | set _dragowner $w |
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125 | break |
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126 | } |
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127 | set w [winfo parent $w] |
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128 | } |
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129 | set _dragx $x |
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130 | set _dragy $y |
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131 | set _dragdata $d |
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132 | set _lastcursor [$widget cget -cursor] |
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133 | $widget configure -cursor $_dcursor |
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134 | } else { |
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135 | set _dragwin "" |
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136 | set _dragowner "" |
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137 | set _dragx "" |
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138 | set _dragy "" |
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139 | set _dragdata "" |
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140 | } |
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141 | } |
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142 | |
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143 | # ---------------------------------------------------------------------- |
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144 | # USAGE: _do_scan <x> <y> ?<operation>? |
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145 | # |
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146 | # Invoked as the user moves the mouse pointer during a drag-n-drop |
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147 | # operation. Scans for a widget at the given <x>,<y> root window |
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148 | # coordinate that will accept the drag data. |
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149 | # ---------------------------------------------------------------------- |
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150 | itcl::body Rappture::Dragdrop::_do_scan {x y {option indicate}} { |
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151 | if {"" != $_dragowner} { |
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152 | set dx [expr {abs($x-$_dragx)}] |
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153 | set dy [expr {abs($y-$_dragy)}] |
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154 | |
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155 | # moved significantly away from click? |
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156 | if {$dx > 3 || $dy > 3} { |
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157 | set win [winfo containing $x $y] |
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158 | if {"" != $win} { |
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159 | set found 0 |
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160 | set wx [expr {$x-[winfo rootx $win]}] |
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161 | set wy [expr {$y-[winfo rooty $win]}] |
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162 | while {"." != $win} { |
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163 | # find the containing win that handles dragdrop and |
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164 | # accepts the given data type |
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165 | if {[catch {$win dragdrop $option -op end -from $_dragowner -to $win -x $wx -y $wy -data $_dragdata} result] == 0 && [string is boolean -strict $result] && $result} { |
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166 | if {"" != $_lasttarget && $_lasttarget != $win} { |
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167 | # if we had a different target, cancel it |
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168 | catch {$_lasttarget dragdrop cancel} |
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169 | } |
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170 | set _lasttarget $win |
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171 | set found 1 |
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172 | |
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173 | # if this is a finalize operation, then send final |
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174 | # message to starting side |
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175 | if {$option == "finalize"} { |
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176 | catch {$_dragowner dragdrop finalize -op start -from $_dragowner -to $win -x $wx -y $wy -data $_dragdata} |
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177 | } |
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178 | break |
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179 | } |
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180 | set win [winfo parent $win] |
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181 | } |
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182 | |
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183 | if {!$found && "" != $_lasttarget} { |
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184 | # no drop target at this point? cancel any previous target |
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185 | catch {$_lasttarget dragdrop cancel} |
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186 | set _lasttarget "" |
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187 | } |
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188 | } |
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189 | } |
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190 | } |
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191 | } |
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192 | |
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193 | # ---------------------------------------------------------------------- |
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194 | # USAGE: _do_drop <x> <y> |
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195 | # |
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196 | # Invoked when the user releases the mouse pointer during a drag-n-drop |
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197 | # operation. Tries to send the drag data to the widget at the current |
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198 | # <x>,<y> root window coordinate to complete the operation. |
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199 | # ---------------------------------------------------------------------- |
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200 | itcl::body Rappture::Dragdrop::_do_drop {x y} { |
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201 | if {"" != $_dragowner} { |
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202 | _do_scan $x $y indicate |
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203 | _do_scan $x $y finalize |
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204 | $_dragwin configure -cursor $_lastcursor |
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205 | } |
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206 | } |
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207 | |
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208 | # ---------------------------------------------------------------------- |
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209 | # USAGE: dd_get_source <widget> <x> <y> |
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210 | # |
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211 | # Derived classes override this method to look at the given <widget> |
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212 | # and <x>,<y> coordinate and figure out what data value the source |
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213 | # is exporting. Returns a string that identifies the type of the |
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214 | # data. This string is passed along to targets via the dd_scan_target |
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215 | # method. If the target may check the source type and reject the data. |
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216 | # ---------------------------------------------------------------------- |
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217 | itcl::body Rappture::Dragdrop::dd_get_source {widget x y} { |
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218 | return "?" |
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219 | } |
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220 | |
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221 | # ---------------------------------------------------------------------- |
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222 | # USAGE: dd_scan_target <x> <y> <data> |
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223 | # |
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224 | # Derived classes override this method to look within themselves at |
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225 | # the given <x>,<y> coordinate and decide whether or not it can |
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226 | # accept the <data> type at that location. Returns 1 if the target |
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227 | # accepts the data, and 0 otherwise. |
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228 | # ---------------------------------------------------------------------- |
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229 | itcl::body Rappture::Dragdrop::dd_scan_target {x y data} { |
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230 | return 0 |
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231 | } |
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232 | |
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233 | # ---------------------------------------------------------------------- |
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234 | # USAGE: dd_finalize drop -op start|end -from <w> -to <w> \ |
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235 | # -x <x> -y <y> -data <data> |
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236 | # USAGE: dd_finalize cancel |
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237 | # |
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238 | # Derived classes override this method to handle the end of a drag |
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239 | # and drop operation. The operation can be completed with a successful |
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240 | # drop of data, or cancelled. Returns 1 if drop was successful, and |
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241 | # 0 otherwise. |
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242 | # ---------------------------------------------------------------------- |
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243 | itcl::body Rappture::Dragdrop::dd_finalize {option args} { |
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244 | return 0 |
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245 | } |
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